Piston means for gas-operated firearms



2 Sheets-Sheet 1 D. M.- WILLIAMS Filed Oct. 31, 1941 My e0 for PISTON MEANS FDR GAS-OPERATED FIREARMS Feb. 8, 1944.

Feb. 8, 1944. o. M. WILLIAMS PISTON MEANS FOR GAS-OPERATED FIREARMS Filed Oct. 3],, 1941 2 Sheetsheet 2 I n uenf an 7 iDaw'd N. M'lfr'am s Patented Feb. 8, 1944 I 1 UNlTED STATES oer-log.

PISTON MEANS FOR GAS-OPERATED FIREARMS Application October 31, 1941, Serial No. 417,254

g 6 Claims.

The present invention relates to improvements in gas-operated self-loading firearms, that is to say, firearms of the type wherein gas pressure developed by the discharge of the cartridge is caused to impinge against a piston or its equivalent, which, in turn, effects the retraction of the breech-bolt and the extraction and ejection of the just-fired cartridge. More particularly, the presentinvention relates to improvements in the piston-means for such firearms and constitutes improvements over my co-pending application, Serial No. 362,943, filed October 26, 1940.

One of the objects of the present invention is. to provide superior piston-means for gas-operated firearms, which may be produced at a low cost for manufactur and which may be relied upon to render service over long periods of use.

Another object of the present invention is to provide a gas-operated firearm-structure with superior piston-means whereby a high degree of freedom is achieved from the deleterious effects of residues from powder gases.

A still further object of the present invention is to provide superior means for a gas-operated firearm whereby a piston-member may be guided in a predetermined path of movement without occasioning the binding of such piston.

Still another object or the pre nt inv ti n is to provide superior means in a gas-operated firearm-structure whereby an actuating piston may be effectively limited in its actuating stroke without causing the said piston to jam or become unduly fouled with residues from powder gases, etc.

With the above and other objects in view, as will appear to those skilled in the art from the present disclosure, this invention includes all features in the said disclosure which are novel over the prior art and which are not claimed in any separate application.

In the accompanying drawings, in which certain modes of carryin out the present invention are'shown for illustrative purposes:

Fig.1 is a broken view inside elevation of a firearm-barrel equipped with the improved piston-means of the present invention, the piston proper being shown in its normal forward position;

Fig. 2 is a broken view partly in side elevation and partly in vertical central-longitudinal section of the barrel and piston-means, with the piston proper shown in its normal position;

Fig. 3 is a transverse sectional view taken on the line 3-3 of Fig. 2;

Fig. 4 is a similar view but taken on the line 4-4 of Fig. 2;

Fig. 5 is a horizontal sectional view taken on the line '.i5 of Fig. 2, but with the piston shown in its rearmost position;

Fig. 6 is a view looking toward the rear face of the tubular top-member;

Fig. '7 is a view of the tubular stop-memberin side elevation;

Fig. 8 is a view looking toward the front end of the tubular stop-member;

Fig. 9 is a view of'the tubular 'stop member in central-longitudinal section; and

Fig. 10 is a perspective view of the tubular stop-member;

Fig. 11 is a view in front elevation 'of a modified form of tubular stop-member; and

Fig..12' is a sectional view thereof taken on the line I2--l2 of Fig. 11.

The' particular firearm-structure herein chosen for purposes of illustrating the presentinvention in Figs. 1 to 10, inclusive, includes a barrel l5 suitable for use as a component of an automatic gasperated firearm and having the usual axial bore 1 l6 extending therethrough and through which bullets are'forwardly propelled in the usual manner of firearms. At a, point intermediate its respective opposite ends and preferably nearer the breech-end than the muzzle, the barrel I5 is formed with an integral depending cylinder-lug I! having a rearwardly-opening piston-chamber l8 therein, and provided with a relatively-heavy front-wan l9. V

The forward portion of the piston-chamber It in the cylinder-lug I1 i of smooth cylindrical form, while the rear portion thereof'is slightly enlarged in diameter and provided with internal threads 20. As a result-0f the difierence in diameters of the respective frontand rear portions of the piston-chamber l8, a rearwardly-facing annular sealing-shoulder 2] results, against which is normally seated the forward face of a slender annular sealing-lip 22'formed at the forward end of a ring-like or tubular stop-member generally designated by'the"reference character 23. The said stop-member is provided with external threads 24 which interfit with the threads 20 within the rear portion of the piston-chamber [8 in the cylinder-lug H, as is shown especially wellin Figs. 2 and 5.

The-tubular stop-member 23 above referred to is provided with an axial passage 25 extending therethrough from front to rear and outwardly flared at its forward end to form a forwardlyfacing conically-contoured sealing-seat 26. In

depths of the tool-receivin notches 27, as is especially well shown in Fig. 9.

As previously pointed out, the forward portion of the piston-chamber I8 is of smooth cylindrical form while the rear portion thereof is internally threaded, as is especially well shown in Fig. 5. Leading forwardly and upwardly from the forward portion of the piston-chamber I8 is a gaspassage 29 which communicates at its upper end with the bore It in the barrel I 5, as is shown especially well in Fig. 2. The lower end of the said gas-passage 29 intersects the rear face of the front-wall I 9 of the cylinder-lug I! at a point slightly below the upper end thereof. The said gas-passage 29 is in line with a notch-like clearance-passage 38 formed in the rear lower edge of the cylinder-lug l7 and through which a drill may be passed in an upWardly-and-forwardlyinclined direction to produce the said gas-passage 29'. The ring-like stop-member 23' extends forwardly beyond the forward limit of the notchlike clearance-passage 30, and aided by the engagement of its sealing-lip 22 with: the sealingshoulder 2l' in the piston-chamber: I8, the said stop-member prevents the escape of gases from the forward portion of the said piston-chamber outwardly through the said clearance-passage 30.

Installed in the forward portion of the pistonchamber I8 with a close sliding fit enabling it to axially reciprocatetherein, is the cylindrically contoured head 31' of a piston generally designated by the reference character 32'. A difference of about .002" in the diameters-of the head 3| and the forward portion of the piston-chain her It is preferred. Thesaid piston in addition to its said head 3! also includes a cylindricallycontoured stem 33 of lesser diameter than the said head 3i. The said stem 33 is formed integral with and projects rea-rwardly from the head 3| and extends through the ring-like stop-member 23 and has a sliding fit with respect to the respective inner faces of the annular series of guide-pads 28 at the rear end of the said stop-' member 23, as is especially well shown in Figs. 2 and 3.

At the junction point of its head 3| and stem 33, the piston 32 is formedwith a rearwardlyfacing conically-contoured annular se'aling-surface 3% which is adapted to engage with the similarly-contoured but forwardly-facing sealingseat 26 in the forward portion of the tubular stop-member 23 around the forward terminus of the axial passage therein.

As will be seen particularly well by reference to Figs. 2 and 4, the stem 33 of the piston 32 fits the forward portion of the axial passage 25 in the stop-member 23 with considerable freedom to provide an annular ring-like passage 35 which communicates at its rear end with the'forward portions of the respective tool-receiving notches 21' in the stop-member 23. all for purposes as will more fully hereinafter appear.

Normally the piston 32 is at the limit of its i ward travel of the piston forward movement as shown in Figs. 1 and 2, in which position the forward face of the head 3| of the said piston is in engagement with the rear face of the front-wall it of the cylinder-lug H. The piston 32 may actuate a wide variety of mechanisms of automatic firearms such, for instance, as an action-slide 36 represented by broken lines in Fig. 1 and which per se forms no essential feature of the present invention. The action-slide St or its equivalent is normally yieldingly pressed forwardly by a helical spring 3'! or its equivalent. A mechanism suitable for actuation by the piston and associated elements of the present invention is disclosed in my copending application above referred to.

Operation Forthe purpose of making clear the functioning of the piston-means above described and shown in the accompanying drawings, it may be assumed that the firearm of which the barrel l5 forms a part, is loaded. The discharge of the firearm will cause a bullet to be forced forwardly through the bore it of the barrel l5 with the result that the gas pressure from the discharge of the just-fired cartridge will pass downwardly and rearwardly in an inclined path from the it of the barrel l5 through the inclined gas-passage 29. The gas under pressure passing through the said gas-passage 29 will first impinge upon only that relatively-small area of the forward face of the head 3! of the piston 32 which now covers the lower end of the said gas-passage. The piston32 will be forced sharp- 1y rearwardly by the gas pressure and Will then immediately have the entire area of the front face of its-head- 3i exposed to the gas, and the movement of the piston will continue until its annular sealing-surface 34 engages with the annular sealing-seat 2 6 at the forward end of the tubular stop-member 23, as is shown particularly well in Fig. 5. By the engagement just referred to, not only will the rearward movement of the piston 32 be checked after a rela- 1- tively-short movement, but the appreciable escape of gases rearwardly from the piston-chamber l8 will be prevented. By this sealing engagement of th piston and the stop-member, the gas pressure within. the bore N5 of the barrel l5 may be prevented from falling to a harmful extent before the bullet has been fully energized and has passed outwardly from the front end of the said bore.

The very rapid though relatively-short rear- 32 as above described, will impart to the action-slide 35 or other desired feature of a firearm, a similar rearward movement, which latter movement, however, will continue after the said piston has ceased its rearward movement. When the energy developed by the discharge of the firearm and the action above referred to has dissipated itself, the action-slide 3B or its equivalent will return to its forward position under the urge of a spring such as 3! and will again restore the piston to the position in which it is shown in Figs. 1 and 2, preparatory to another discharge of the firearm.

Such gas as does rearwardly escape past the head 3! of the piston 32 and the sealing-surface El 5 thereof, will move rearwardly through the annular ring-like passag 35 between the periphery of the stem 33 of the piston and the inner wall of the stop-member 23, thence outwardly through the tooLreceiving notches 21. Under the circumstances just recited, the tool-receiving notches 21, 'andparticularlytheir rear portions;

v The structure ofFz'gs. 11 um Z 12 I The ring-like stop-member 38 shown in Figs.

11 and 12 is suitable for use in lieu of the stop'-' member 23 shown in the preceding figures; The said stop-member 38 is formed upon its outer periphery with threads 39 corresponding to the threads 2% before referred to and, like the same, adapted to interfit with the threads 20, or their equivalent, within the rear portion of the pistonchamber la in the cylinder-lug H.

The tubular stop-member 58 is provided with an axial passage Ml extending therethrough from front to rear and outwardly flared at its forward end to form a forwardly-facing conicallycontoured sealing-seat 4! corresponding to the sealing-seat 26-before referred to. The axial passage it includes a relatively-large-diametered front portion 2 and a relatively-small-diametered rear portion 43. Preferably, the rear edge of the stop-member 38 is formed with a plurality of tool-receiving notches 2-4.

Like the rear portion of the axial passage 25 in the stop-member 23 of the preceding construction, the rear portion 53 of th passage 4!! in the stop-member 38 is sized to accommodate with a free sliding fit the stem of a. piston such as the stem 33 before referred to. On the other hand, theforward portion d2 of th axial pas sage all is enlarged to clear the stem of a piston and permit the latter to reciprocate freely and engage with the sealing-seat 41 or its equivalent without binding and without causing the undue accumulation of residue.

Advantages By supporting the stem 33 of the piston 32 only at a point remote from the sealing-seat 26 of the stop-member 23, the sealing-surface 34 of the piston is enabled to accurately engage the said sealing-seat without cramping action and without causing the piston to bind.

Furthermore, by providing vents for the minute amount of gases and other residues which might escape past the piston-head 3|, the fouling of the guideor bearing-surfaces 28 engaged by the stem 33, is avoided and hence another possible source of maul-functioning is substantially eliminated.

It is especially advantageous to provide the plurality of guide-pads 28, or their equivalent, with gaps therebetween to permit the free egress of gases and residues from the interior of the stop-member 23. By having the notches 21, or their equivalent, extend inwardly beyond the inner edges of the guide-pads 26, gases and residues are permitted an escape without approaching even closely to the said bearing-pads, or their equivalent.

The invention may be carried out in other specific ways than those herein set forth without departing from the spirit and essential characteristics of the invention, and the present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

I claim:

1. A firearm-structure including in combination: a barrel having an axial bore therethrough;

a cylinder located adjacent the saidbarrel and provided with a piston-chamber and with agasp'a'ssage connecting the said piston-chamber with thebore of the said barrel; a piston reciprocating in the piston-chamber of the said cylinder and including a head having a sliding fit directly in the saidpiston-chamber, the said piston also having a relatively-slender stem projecting from the said head; and a ring-like member having an axial passage therethrough and extending part way into the piston-chamber of the said cylinder and fitting over the stem of the said piston, the said member having the outer portion of its axial passage sized to be engaged with and guide the stem of the said piston and having an inner portion of its said axial passage enlarged to clear the stem of the said piston but of substantially smaller diameter than the head of the piston, whereby thering-like member serves as a stop to limit outward movement of said piston, the said member also being formed with vent-means communicating with the enlarged inner portion of the axial passage in the said member.

2. A firearm-structure including in combination: a barrel having an axial bore therethrough; acylinder located adjacent the said barrel and provided with a piston-chamber and with a gaspassage connecting the said piston-chamber with the bore of the said barrel; a piston reciprocating in the piston-chamber of the said cylinder and including a head and a relatively-slender stem projecting from the said head; and a ring-like All member having an axial passage therethrough and extending part way into the piston-chamber of the said cylinder and fitting over the stem of the said piston, the said member having the outer portion of its axial passage sized to be engaged with and guide the stem of the said piston and having an inner portion of its said axial passage enlarged to clear the stem of the said piston, the said member also being formed in its outer edge with a plurality of notches extending into communication with the enlarged inner portion of the axial passage in the said member.

3. A firearm-structure including in combination: a barrel having an axial bore therethrough; a cylinder located adjacent the said barrel and provided with a piston-chamber and with a gaspassage connecting the said piston-chamber with the bore of the said barrel; a piston reciprocating in the piston-chamber of the said cylinder and including a head and a relatively-slender stem projecting from the said head; and a ringlike stop-member engaged at its inenr end by the head of the said piston to check the movement of the latter and extending part way into the piston-chamber of the said cylinder and having an axial passage therethrough receiving the stem of the said piston and materially larger than the diameter of the said stem to provide an annular axial gas-passage, the said stop-member being formed in the outer portion of its axial passage with a plurality of circumferentially-spaced apart guide-pads projecting radially inwardly into position to guide the stem of the said piston.

4. A firearm-structure including in combination: a barrel having an axial bore therethrough; a cylinder located adjacent the said barrel and provided with a piston-chamber and with a gaspassage connecting the said piston-chamber with the bore of the said barrel; a piston reciprocating in the piston-chamber of the said cylinder and including a head and a relatively-slender stem projecting from the said head; and a ring-like stop-member engaged at its inner end by the head of said piston to check the movement of the latter and extending part way into the pistonchamber of the said cylinder and having an axial passage therethrough receiving the stern of the said piston and materially larger than the diameter of the said stem to provide an annular axial gas-passage, the said stop-member being formed in the outer portion of its axial passage With a plurality of circumferentially-spaced-apart guide-pads projecting radially inwardly into position to guide the stem of the said piston, the said stop-member also being formed with ventmeans communicating with the axial passage in the said stop-member at a point inwardly of the said guide-pads.

5. A firearm-structure including in combination: a barrel having an axial bore therethrough; a cylinder located adjacent the said barrel and provided with a piston-chamber and with'a gaspassage connecting the said piston-chamber with the bore of the said barrel; a piston reciprocating in the piston-chamber of the said cylinder and including a head and a relatively-slender stem projecting from the said head; and a ringlike stop-member engaged by the head of the said piston to check the movement of the latter and extending part way into the piston-chamber of the said cylinder and having an axial passage therethrough receiving the stem of the said piston and materially larger than the diameter of the said stem to provide an annular axial gasiii) 1, notches extending into passage; the said stop-member being formed in the outer portion of its axial passage with a plurality of circumferentially-spaced-apart guidepads projecting radially inwardly into position to guide the reciprocating movement of the stem of the said piston.

6. A firearm-structure including in combination: a barrel having an axial bore therethrough; a cylinder located adjacent the said barrel and provided with a piston-chamber and with a gaspassage conneotingthe said piston-chamber with the bore of the said barrel; a piston reciprocating in the piston-chamber of the said cylinder and including a head and a relatively-slender stem projecting from the said head; and a ringlike stop-member engaged by the head of the said piston to check the movement of the latter and extending part way into the piston-chamber of the said cylinder and having an axial passage therethrough receiving the stem of the said piston and materially larger than the diameter of the said stem to provide an annular axial gas-pasthe said stop-member being formed in the outer portion of its axial passage with a plurality of circumferentially-spaced-apart guide-pads projecting radially inwardly into position to guide the reciprocating movement of the stem of the said piston, the said stop-member also being formed in its outer edge with a plurality of communication With the axial passage in the stop-member at a point inwardly of the said guide-pads.

DAVID M. WILLIAMS. 

